The operator's cab for an earthworking vehicle, such as a track-type tractor, is normally mounted on a frame of the vehicle by a plurality of supporting posts. The posts provide roll-over protection for the operator and are oftentimes attached to the frame by resilient bushing assemblies or the like for substantially isolating the operator's cab against vibrations occurring during vehicle operation. Typical mountings of this type are disclosed in U.S. Pat. Nos. 3,036,858, 3,203,728; 3,572,819; and 3,623,754.